Toxicity test methods extraction solution

Solutions must be concentrated or the constituents must be isolated before trace amounts of the various organics present as complex mixtures in environmental water samples can be chemically analyzed or tested for toxicity. A major objective is to concentrate or isolate the constituents with minimum chemical alteration to optimize the generation of useful information. Factors to be considered in selecting a concentration technique include the nature of the constituents (e.g., volatile, nonvolatile), volume of the sample, and analytical or test system to be used. The principal methods currently in use involve (1) concentration processes to remove water from the samples (e.g., lyophilization, vacuum distillation, and passage through a membrane) and (2) isolation processes to separate the chemicals from the water (e.g., solvent extraction and resin adsorption). Selected methods are reviewed and evaluated. 

The principal regulatory method to protect consumers from marine toxins in food is the mouse bioassay. It measures the time to death after intraperitoneal injection of a toxic extract, and toxicity is expressed as the amount of toxin (usually in micrograms) or toxin equivalents (eq) per gram (or 100 g) of shellfish tissue, standardized against a reference toxin solution. As it is a reliable indicator of human oral toxicity, the mouse bioassay is obligatory prior to commercialization of seafood in many countries. However, this biological test does not allow for specification of toxins or studies on the formation and effect of individual toxins. In addition, it has a high variability ( 20%) and low sensitivity, lacks specificity, and often has detection limits too near to the accepted threshold. Yet, the major limitation of the mouse bioassay is of ethical and political nature due to the use of live animals. 

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